<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    #d1{
      /*left/right/top/bottom单独某一个方向添加边框*/
      border: 10px inset red;
      width: 100px;
      height: 200px;
      /*设置圆角 值越大越圆*/
      border-radius: 100px;

    }
    #d2{
        width: 100px;
        height: 100px;
        border: 1px solid blue;
        padding-left: 50px;
        padding-top: 50px;
        /*默认情况下给元素添加内边距会影响元素宽高*/
        box-sizing: border-box;/*不再影响宽高*/
    }
  </style>
</head>
<body>
<div id="d1">边框</div>
<div id="d2">内边距</div>

</body>
</html>